276 
Miscellaneous . 
On the Histological Constitution of certain Nematodes of the Genus 
Ascaris. By M. Leon Jammes. 
Naturalists who have studied the histology of the Nematodes 
up to the present time have asserted that the layer named by them 
granular layer was not cellular in the adult. Leuckart, however, 
thought that there existed an epithelial layer formed by very small 
elements, situated internal to and close against the muscle-cells. 
In the investigations in which I am engaged, on certain species 
of Nematodes, and in particular Ascaris megalocephala , A . lumbri- 
coides (calf), and A. suilla (Dujardin), I have never been able to 
establish the existence of this layer. With the aid of the histo- 
logical apparatus in use at the Faculty of Sciences of Toulouse I 
have long sought in the granular layer for any traces of an ectoderm. 
The granular layer is limited on one side by the cuticle, on the 
other by the muscular layer. 
But, on the other hand, these researches have brought to light 
certain particulars relating to the granular layer : transverse sec- 
tions at the horizon of the oesophagus show the continuity and 
structural identity of the oesophageal nervous ring and of the 
granular layer. Both are made up of fibrils interspersed with cells. 
The fibrils of the nervous ring on arriving at the body-wall bend 
inwards and distribute themselves between the cuticle and the 
muscular layer; after this the nervous system and the muscular 
layer affect connexions so fine that it is impossible to assign their 
exact limits. 
Longitudinal sections at different horizons show little beds of 
cells in the granular layer, often disposed in several rows but never 
forming a continuous epithelium. 
These cells present various appearances : rarely cubic, sometimes 
rounded, most often flattened parallel to the body- wall, they bear a 
variable number of prolongations. It is these prolongations which 
contribute to give the layer its fibrillar and felted aspect in the 
sections. 
No intercellular substance is ever found between them. 
The cells of the granular layer are stained a uniform violet by 
chloride of gold, whilst this reagent colours the cuticle rose and 
purple. The external segmentation as revealed by this infiltra- 
tion does not correspond, at least in the adult, with any internal 
metamerization. 
The great similitude of structure of the granular layer and of the 
nervous system leads us to think that the granular layer represents 
the ectoderm. This latter would differ much in its constitution 
from the ectoderm of other Metazoa ; it would be made up, in effect, 
of neuro-epithelial elements, and the nervous system described by 
authors would only be a condensation of this mass at different points 
in the body. 
However, this idea needs corroborating by embryological re- 
searches, in which I am now engaged. — Comptes Hendus , July 7, 
1890, p. 65. 
